A method for producing a force-measuring element having at least one articulation site which separates a region of the force-measuring element into two connected sub-regions which deflect relative to one another is known. In a first step, material is removed from a force-measuring element blank so that it is separated into two sub-regions which can be deflected relative to one another. In a next method step, it is tested whether the deflection behavior of the sub-regions created by the articulation site corresponds to a predefined specification. The expression “deflection behavior” should be understood broadly herein and particularly covers the aspects of the mobility of the articulation site, the articulation direction of the sub-regions that are articulated to one another and the exact position of the rotation point. A deviation measured for this purpose is correspondingly corrected in a next method step in that material is removed at the articulation site with a cutting tool, for example, with a file. This material removal can be carried out by machine but is preferably carried out by hand, by a trained specialist.
A disadvantage of this method is that, typically, an articulation site correction of this type does not entirely remedy the measured deviation. Additionally, due to the material removal by cutting, a force is exerted on the articulation site which in turn can cause an undesired plastic deformation of the bending body produced due to the articulation site, or tensions in the material of the articulation site.
From WO 2008/145426 A1, a force measuring element is known wherein the articulation site correction takes place through plastic deformation of a deformation site of the force-measuring element. In this force-measuring element, therefore, during the articulation site correction, material removal at the articulation site itself is entirely dispensed with.
It is also known that force-measuring elements can be produced through material removal by a laser from a suitable force-measuring element blank. For example, from DE 102 29 016 A1, a pivot bearing for weighing bridges which is machined by laser cutting from a monolithic basic body is known. A correction of the articulation sites of the pivot bearing is, however, no longer carried out following production.
Further force-measuring elements are known from U.S. Pat. No. 3,968,683 A and EP 0 164 862 A2. The load-dependent deformation of these force-measuring elements is detected with strain gauges which can be adjusted through material removal by a laser. However, a correction of the articulation site geometry is not provided with these force-measuring elements either.
A method for producing a force-measuring element wherein a correction of the articulation site geometry takes place through material removal by a laser is known from DE 101 39 443 A1. In this method, the force-measuring element is induced to oscillate during the material removal and the oscillation change arising from the material removal is detected as a parameter, for example, for setting the sensitivity of the force-measuring element. For this purpose, the oscillation change is measured instantaneously and the material removal is continued until the measured oscillation corresponds to a pre-determined specification.
A disadvantage of this method is that only during the material removal is it determined whether the desired specification can be achieved at all. As a consequence of this, the known method operates less efficiently since material removal is also carried out at force-measuring elements for which the desired specification can no longer be realized by material removal of this type. In addition, a force-measuring element of this type becomes completely unusable due to this material removal and must therefore necessarily be classified as a defective product. This is disadvantageous particularly with regard to the costs associated with the production of the force-measuring element.